Portable transmitter apparatus with selective, diverse antenna means



April 23, 1963 4' 1 :I 21 l 26:6? 0 o .25 fi o O F' MITCHELL J. PORTABLETRANSMITTER APPARATUS WITH SELECTIVE Filed Aug. 3, 1959 DIVERSE ANTENNAMEANS 2 Sheets-Sheet 1 INVENTOR.

April 23, 1963 J. F. MITCHELL PORTABLE TRANSMITTER APPARATUS WITHSELECTIVE DIVERSE ANTENNA MEANS 2 Sheets-Sheet 2 Filed Aug. 5, 1959INVENTOR.

United States Patent 3,037,117 PORTABLE TRANSMlTTER APPARATUS WITHSELECTIVE, DXVERSE ANTENNA MEANS John F. Mitchell, Berkeley, lit,assignor to Motorola, Inc, Chicago, Ill., a corporation of IllinoisFiled Aug. 3, 1959, Ser. No. 831,33t} 6 Claims. (1. 325-118) Thisinvention relates generally to portable radio equipment and moreparticularly to an effective antenna arrangement for a pocket sizetransmitter and/ or receivers which may be worn by a man on foot anduseable by him without interfering with his normal duties.

Portable radio equipment has been provided to permit a person on foot totransmit and/or receive a message by radio. One such transmitter unit iscovered by Patent No. 2,810,068 assigned to the assignee of the presentinvention. While such units have been of great value there has been aproblem that the units must be held in the hand of the operator andtherefore interfere with his normal duties, and are of a size to bediflicult to hold. It has been desired'to have units which are of smallsize and light weight and which can be worn by a person in the manner sothat'they do not interfere with his desired operations. There has alsobeen the problem of providing an effective antenna arrangement forportable units so that they may be used to transmit and/ or receivesignals over a substantial distance.

It is therefore an object of the present invention to provide a radiounit for use by a person on foot and which may be worn by the user in amanner 'so that it will not interfere with his normal duties.

Another object is to provide a pocket size radio transmitter and/ orreceiver with an antenna arrangement which provides elfective radiocommunication.

A feature of the invention is the provision of a portable radio unitwhich =i-s contained in a pocket size housing which may be worn by theuser, with a self-contained antenna which is normally used, and anextensible antenna which may be used to provide a greater range ofcommunication and which is automatically connected in the circuit whenthe antenna is extended.

Another feature of the invention is the provision of a portable radiotransmitter housing with a microphone connected to the transmitterhousing bya cable which includes a shield oran extra conductor whichserves as the antenna for the transmitter.

.Still another feature of the invention is the provision of a;portabletransmitter contained in apocket size housing and including a telescopicantenna, and a microphone connected to the housing bya cable which mayalso serve as an antenna, with aswitch in the housing being operated byextension and retraction of the telescopic antenna to selectivelyconnect the telescopic antenna or the microphone cable to thetransmitter output.

A further feature of the invention is the provision of a pocket sizeradio transmitter with self-contained batteries which may be worn on thebelt of a user, with a microphone having the operating switch for thetransmitter thereon connected to the housing by a cable, so thatcomplete control is provided by a single element which is easily held inone hand of the user.

The invention is illustrated in the accompanying drawings wherein:

FIG. 1 shows apersonwearing and operating a portable transmitter inaccordance with the invention;

.FIG. 2 shows the transmitter with carrying clip, microphone andantenna;

FIG. 3 illustrates the arrangement of the transmitter chassis, batteriesand antenna within the pocket size housing; and

fihlii? Patented Apr. 23, 1%63 FIG. 4 is a circuit diagram showing thecomplete circuit of the transmitter and the antennas and switchconnected thereto.

In practicing the invention there is provided a pocket size radio unitprovided in a small housing which may be carried in the pocket orclipped on a belt so that it does not interfere with the normal dutiesof the person using the transmitter. Batteries are included in thehousing so that the unit is completley self-contained. The unit may be atransmitter having a microphone connected to the housing through a cableof a length so that the microphone can be placed adjacent the mouth ofthe user while the housing is clipped to his belt. The microphoneincludes an on-off switch which controls the energization of thetransmitter. The microphone cable has a shield or an extra conductorwhich serves as an antenna for radiating signals. A telescopic antennais also included in the housing and is coupled to a switch so that whenthe antenna is extended the telescoping antenna is connected to thecircuit, and when the antenna is retracted into the housing themicrophone cable shield is connected to the transmitter circuit. --Theoutput circuit of the transmitter is connected to ground so that thecable shield is effectively at ground potential for audio frequencies. Areceiver unit may be similarly constructed with a telescoping antennawhichis connected to the receiver circuit when the antenna is extendedand an antenna contained within the receiver housing may be connectedwhen the antenna is retracted.

Referring now to the drawings, in FIG. 1 there is shown a person using atransmitter in accordance with the invention, with the housing ltlclipped to his belt. He is holding the microphone 11 in his hand withthe cord 12 connecting the microphone to the housing extendingsubstantially vertically. The microphone 11 includes an operating switch13 which controls energization of the transmi-tter. The microphone cable12 has a shield which serves as the antenna for the transmitter as willbe more fully explained.

In FIG. 2 the back side of the housing 10 is in view, and the clip 15which will support the unit on a belt or the like is shown. Thetelescoping antenna 16 provided in the housing 10 is extended to serveas the signal radiator for the unit. A switch 17 is provided forselecting one of two frequencies which may be used by the transmitter.

, In FIG. 3 the transmitter is shown with a part of the housing removed.The transmitter chassis 20 is provided in a frame 21 which also holdsbatteries 22 for energizing the transmitter. It is therefore apparentthat the unit is entirely self-contained. A switch 23 is provided havinga portion extending in the path of the antenna 16, a indicated by thedotted. lines 18, to be operated when the antenna 16 is withdrawn fromthe housing as will be i'further explained. A pivotally mounted clip 25holds 'audio signals from the microphone 11 are applied to input circuitincluding transformer 35. To cont-rol'the deviation of modulation, theaudio signals are applied through diifen entiating circuit 36, and arethen symmetrically clipped "by the circuit including transistor 37, andintegrated by the circuit 38. A controlled amount of the audio isderived from potentiometer 39 and is applied to the grid of modulatortube 32.

The carrier frequency as Well as the frequency modulation thereof ismultiplied by the stages including tubes for audio frequency signals.

40, 41 and 42 and applied to the driver stage including tube 43. Thisapplies the output signals to output transformer 44 which is connectedto a tap on the output coil 45. The output coil is connected betweenground and switch 23 which selectively connects the output to thetelescoping antenna 16 or to the conducting shield 24 on the microphonecable 12.

It will be apparent that with the switch 23 in the position shown, themovable contact 46 engages the resilient contact 47 which is connectedto the lead 48 connected to the telescopic antenna 16. The switch is inthis position when the antenna is withdrawn. When the antenna 16 istelescoped into the housing the end 26 of the antenna will engage thearm 50 of the switch 23'. This will cause the movable arm to move to thedotted position so that the movable contact 46 engages the resilientcontact 51 which is connected through conductor 52 to the shield 24.Accordingly when the antenna is retracted the output coil 45 isconnected to the shield 24 of the microphone cable 12.

As shown in FIG. 1 the microphone cable is held in a substantiallyvertical position when the microphone is being used so that effectiveradiation therefrom is provided. As the output coil 45 of thetransmitter is grounded (FIG. 4) the shield 24 is effectively groundedAccordingly when the shield 'is used as an antenna, there is noobjectionable noise pickup by the shield to introduce noise into theaudio input of the transmitter circuit.

It may be desired to transmit a tone along with the audio transmissionto operate a control at the receiver indicating the particulartransmitter from which the signal is being received. To accomplish thisa bridge type transistor oscillator 55 is provided which may include areed device 56 for controlling the frequency. In the event that aplurality of systems are operating on the same carrier frequency, thecontrol tone provided along with the transmissions may be used to renderonly selected receivers operative to reproduce the transmitted signals.The signals from the oscillator 55 are applied to the grid of theoscillator 30 to directly frequency modulate the Wave produced thereby.Accordingly the output of the oscillator 30 is frequently modulated, andthis modulated wave is further frequency modulated by the audio signalsin the modulator 32.

As previously stated a switch 17 may be provided on the housing toselect one of a plurality of frequencies. A second oscillator includingtube 57 is provided which is connected to the modulator 32 to provideoscillations thereto. A crystal 58 controls the frequency of thisoscillator. The oscillators 30 and 57 are selectively rendered operativeby switch 17 which selectively applies heater current to the tube 30 orthe tube 57. The tone generator 55 may also be used to modulate theoscillator 57, or the oscillator 57 may provide transmission at afrequency wherein the control tone is not used.

It is therefore seen that a portable transmitter is provided which maybe very conveniently used by a person on foot without interfering withhis other operations. The main housing may be secured to the belt or theuser either by the clip 15 as shown in PEG. 2, or by a separate casewhich may be provided. The microphone 11 is very small so it canconveniently be held in the hand when the transmitter is being used andmay be placed in a pocket or be otherwise carried when not being used.The operating switch for the transmitter is provided on the microphoneso that it may be operated by the fingers of the hand holding themicrophone.

The shield for the microphone cable, or an extra conductor in the cable,serves as an antenna for the transmitter so that a separate element isnot required. Inasmuch as the cable between the microphone and thehousing for the transmitter extends substantially vertically while thetransmitter is used, the shield forms an effective signal radiator. Ifit is desired to provide communications over longer ranges, thetelescoping antenna may be extended from the housing. By holding thetelescoping antenna at a high elevation improved signal radiation may beobtained. The telescoping antenna is coupled to a switch whichautomatically connects the output coil of the transmitter to the shieldor to the telescoping antenna.

A small portable receiver may also be provided with a self containedantenna and a telescoping antenna with the telescoping antenna operatinga switch when it is extended and retracted. The self-contained antennais normally connected to the receiver circuit through the switch,

and when the antenna is extended it is connected to the receivercircuit.

This provides more effective signal pick-up when needed to extend therange of communications.

I claim:

1. A portable radio unit including in combination, a pocket size housingcontaining a chassis including cornponents forming a radio circuit,batteries in said housing for energizing said circuit, switch means insaid hous ing connected to said circuit, said unit including meansforming a first antenna and connected to said switch means, a secondextensible antenna mounted in said housing to be telescoped therein andto extend therefrom, and means electrically connecting said secondantenna to said switch means, said second antenna including a portionpositioned to mechanically engage said switch means to operate the sameto connect said second antenna to said radio circuit when said secondantenna is extended, said switch means being operated by said secondantenna to connect said first antenna to said radio circuit when saidantenna is telescoped into said housing.

2. A portable radio unit including in combination, a housing containinga chassis including components forming a radio circuit, batteries insaid housing for energizing said circuit, switch means in said housingconnected to said circuit, said unit including means con tained thereinforming a first antenna connected to said switch means, said switchmeans normally connecting said first antenna to said radio circuit, asecond extensible antenna mounted in said housing to be telescopedtherein and to extend therefrom, and means electrically connecting saidsecond antenna to said switch means, said second antenna including aportion positioned to mechanically engage said switch means when saidsecond antenna is extended to operate said switch means to dis connectsaid first antenna and connect said second antenna to said radiocircuit, said switch means being operated by said second antenna whensaid second antenna is telescoped into said housing to disconnect saidsecond antenna and connect said first antenna to said radio circuit.

3. A portable radio transmitter including in combination, a housingadapted to be secured to the body of a person using the transmitter, aradio transmitter chassis having input and out-put circuits mounted insaid housing, batteries in said housing for energizing the transmitter,switch means in said housing connected to said output circuit, amicrophone unit including an energizing switch adapted to be held in thehand of the person using the transmitter, a cable connecting saidmicrophone unit to said transmitter chassis to apply signals to saidinput circuit thereof, said energizing switch selectively connectingsaid batteries to said chassis through said cable, said cable having aconductive shield connected to said switch means and selectivelyconnected thereby to said output circuit to serve as a signal radiatorfor the transmitter, an extensible antenna mounted in said housing to betelescoped therein and to extend therefrom, and means electricallyconnecting said antenna to said switch means, said antenna including aportion positioned to mechanically engage said switch means to operatethe same to connect said antenna to said output circuit when saidantenna is extended, said switch means being operated by said antenna toconnect said shield to said output circuit when said antenna istelescoped into said housing.

4. A portable radio transmitter including in combination, a housingcontaining a radio transmitter chassis having input and output circuits,said output circuit including a winding having low impedance at audiofrequencies with said winding being connected between a referencepotential and an output terminal, said housing having means forsupporting the same at the waist of the user, batteries in said housingfor energizing said chassis, a microphone unit adapted to be held in thehand of the user of the transmitter, first switch means in saidmicrophone unit including an energizing switch, a cable connecting saidmicrophone unit to said trans mitter chassis to apply signals to saidinput circuit thereof, said cable having a length to permit holding saidmicrophone unit adjacent the mouth of the user, said energizing switchselectively connecting said batteries to said chassis through saidcable, second switch means in said housing connected to said outputterminal, said cable having a conductive shield connected to said secondswitch means and selectively connected thereby to said output terminalto serve as a signal radiator for the transmitter, said shield beingconnected to the reference potential through said winding to provide aneffective shield for audio signals applied from said microphone unitthrough said cable to said transmitter chassis, and a telescopingantenna mounted on said housing and connected to said second switchmeans to be connected thereby to said output terminal.

5. A portable radio transmitter including in combination, a pocket sizehousing containing elements forming a radio transmitter circuit havingan input and an output, batteries in said housing for energizing saidcircuit, switch means in said housing connected to said output of saidtransmitter circuit, a microphone, a cable connecting said microphone tothe input of said transmitter circuit, said cable having a conductiveshield connected to said switch means and selectively connected therebyto said output of said transmitter circuit to serve as a signal radiatortherefor, an extensible antenna mounted in said housing to be telescopedthereon and adapted to extend therefrom, and means connecting saidantenna to said switch means, said antenna including a portionpositioned to engage said switch means to operate the same to connectsaid antenna to said output of said transmitter when said antenna isextended, and to connect said shield to said output of said transmitterwhen said antenna is telescoped in said housing.

6. A portable radio transmitter including in combina tion, a housingcontaining a radio transmitter chassis having input and output circuits,batteries in said housing for energizing the transmitter, switch meansin said housing connected to said output circuit, a microphone unitincluding an energizing switch, a cable connecting said microphone unitto said transmitter chassis to apply signals to said input circuitthereof, said energizing switch selectively connecting said batteries tosaid chassis through said cable, said cable including conductor meansconnected to said switch means and selectively connected thereby to saidoutput circuit to serve as a signal radiator for the transmitter, anextensible antenna mounted in said housing to be telescoped therein andto extend therefrom, and means electrically connecting said antenna tosaid switch means, said antenna including a portion positioned tomechanically engage said switch means to operate the same to connectsaid antenna to said output circuit when said antenna is extended, saidswitch means being operated by said antenna to connect said conductormeans to said output circuit when said antenna is telescoped into saidhousing.

References Cited in the file of this patent UNITED STATES PATENTS2,063,248 Hansell Dec. 8, 1936 2,361,953 MacDonald Nov. 7, 19442,535,063 Halstead Dec. 26, 1950 2,573,438 Hathaway et a1. Oct. 30, 19512,899,549 Potter Aug. 11, 1959 OTHER REFERENCES Basic Theory andApplications of Transistors, Army Technical Manual TM 11-690, March1959, page 4.

1. A PORTABLE RADIO UNIT INCLUDING IN COMBINATION, A POCKET SIZE HOUSINGCONTAINING A CHASSIS INCLUDING COMPONENTS FORMING A RADIO CIRCUIT,BATTERIES IN SAID HOUSING FOR ENERGIZING SAID CIRCUIT, SWITCH MEANS INSAID HOUSING CONNECTED TO SAID CIRCUIT, SAID UNIT INCLUDING MEANSFORMING A FIRST ANTENNA AND CONNECTED TO SAID SWITCH MEANS, A SECONDEXTENSIBLE ANTENNA MOUNTED IN SAID HOUSING TO BE TELESCOPED THEREIN ANDTO EXTEND THEREFROM, AND MEANS ELECTRICALLY CONNECTING SAID SECONDANTENNA TO SAID SWITCH MEANS, SAID SECOND ANTENNA INCLUDING A PORTIONPOSITIONED TO MECHANICALLY ENGAGE SAID SWITCH MEANS TO OPERATE THE SAMETO CONNECT SAID SECOND ANTENNA TO SAID RADIO CIRCUIT WHEN SAID SECONDANTENNA IS EXTENDED, SAID SWITCH MEANS BEING OPERATED BY SAID SECONDANTENNA TO CONNECT SAID FIRST ANTENNA TO SAID RADIO CIRCUIT WHEN SAIDANTENNA IS TELESCOPED INTO SAID HOUSING.